Do you prefer to run in packs or operate as a loner? Your answer is determined by your genes, a new study claims. It's a big shift in social behavior theory, since scientists previously thought the environment determined social behavior.

For example, scientists thought that where food was sparsely spread around, primates would live in large groups to more efficiently forage. But according to the new findings, which were published in the journal Nature, primates will behave the way their genes tell them to, regardless of food availability.

It's evidence for genetic determinism—the idea that our genes dictate our behavior. But it seems wrong, right? I know I tend to go with the behavior that helps me to avoid hunger most effectively. But Nicholas Wade in The New York Timessums it up thusly:

Advertisement

The Old World monkeys, for example, a group that includes baboons and macaques, live in many habitats, from savanna to rain forest to alpine regions, and may feed on fruit or leaves or grass. Yet all have very similar social systems, suggesting that their common ancestry - and the inherited genes that shape behavior - are a stronger influence than ecology on their social structure.

Michael Skinner, a professor at the Center for Reproductive Biology at Washington State University says, though, that the role of genetics is being overstated here as it has been for decades. Skinner is an expert in epigenetics, which is the study of the environment's impact on genetics.

"There is no genetic-process-only phenomena, as there is no epigenetic-only phenomena. The age of genetic determinism needs to end," he says. Genetics only paints half the picture of human biology.

The new paper also calls into question the "social brain hypothesis," the idea that as primate brains evolved to be larger, they became more capable of managing larger social networks. Says Skinner, after reading the paper:

The article did not mention epigenetics, but did mention the ability of environment to impact brain development and social behavior. Not sure how they think this can occur without epigenetics. ... There will not be a physiological process or tissue function that does not use a combination of genetics and epigenetics.

Genetic determinism bothers me because I'm adopted. I don't like the thought of being at the mercy of DNA I know little about. It also bothers me because it makes people lazy. Folks blame their DNA for their inability to play an instrument, for example, when they've never taken a lesson in their lives.

It bothers Skinner because by studying only genetics and ignoring epigenetics, we're getting only half the biological information on how disease develops. Hundreds of millions of dollars has been spent on genome-wide association studies with the goal of pinpointing genes that cause disease, but most of the genetic anomalies that cause heritable diseases remain undiscovered.

Environmental epigenetics has greater ability to explain non-Mendelian phenomena than genetics. It is not that genetics is not important, it is simply not the only molecular mechanism involved in biology.

Our attachment to genetic determinism doesn't really jive with our (among most Americans', it seems) love of free will. In the science world, however, I kind of get the resistance: many scientists have built their careers on the idea that genes rule. They don't want to give up the throne. But it's time: when it comes to finding the causes of disease, genetics is not working.